tapping head unit lines

[The Tall Man 10+ year member]

Hello,

I have a BMW head unit with "BALANCED line outputs". The outputs currently go to a stock amplifier, that I want to keep. Two questions:

1.) What is the impact of "tapping" these line outputs? I want to tap them and send them to a converter (to RCA) and then to an aftermarket sub amp so I can add a subwoofer. Will the signal be cut in half to both sub amp and the stock amp? Will I notice lower volumes from the stock amplifier? Should I worry about damaging the head unit (it will see a different load when tap the lines)?

2.) What is the difference between BALANCED line outputs, SPEAKER level outputs, and RCA outputs?

Thanks!

TTM

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[fantomas 10+ year member]

Originally posted by The Tall Man  

2.) What is the difference between BALANCED line outputs, SPEAKER level outputs, and RCA outputs?

 

i think balanced line outputs might be mono...like for a sub. speaker level outputs, at least for a hu, are powered by the internal amplifier and go to the speakers. some amps have speaker level inputs. rca outs just go straight to the amp. the voltage is anywhere between 1.5-9 i think.

 

[maylar 10+ year member]

If by "tapping" you mean using an RCA "Y" cable to send the signal to 2 inputs, yes you can do that without any noticible losses. Not a good idea with speaker level or balanced lines though.

RCA outputs use ground as the signal return. The cables are a single wire inside a shielded jacket. This has been the standard audio preamp connection for 50 years.

Balanced lines have a separate wire for signal return. They have better noise rejection than single-ended lines. They use differential drivers and receivers in the equipment, so they're more expensive to implement. Mostly found on studio and high end audiophile equipment.

Speaker level inputs are just that - you can connect them directly to the speaker wires of the head unit. Amps with speaker level inputs are handy when hooking them up to factory decks that don't have preouts.

 

[eengrms 10+ year member]

You'd be better off to tap off of your rear speakers and go into a line-level convertor in your trunk, and then into the amp via RCA. I don't know where your rear speakers are or if it would be difficult to get to, but it would probably work much better. I did that in my Audi witha single amp and sub and it sounds great. I wouldn't want to control a large amp off of it, but a single smaller one would be ok. Make sure you get a decent convertor too, don't buy the cheapo Jensen one at Best Buy.

 

[The Tall Man 10+ year member]

What do you mean by "large amp"?

TTM

 

[eengrms 10+ year member]

A 1000W amp would be large. A 200W amp would not be. What amp are you trying to connect? I'm not saying it wouldn't work for a large amp, but most convertors do not put out 4V, unless you spend about $60 and get a good name brand. Even then it's sketchy.

 

[The Tall Man 10+ year member]

Thinking about a 500.1 JL Audio (it already has balanced line inputs); or a JBL 600.1 (seems to come highly recommended on this list and is cheaper than JLA, but lacks balance inputs from what I know).

Thanks for your replies, too.

TTM